On Nov 7, 2007, at 7:44 AM, John Love-Jensen wrote:
Your Singleton class forward declares a "static Type* ptr", but
doesn't
actually allocate the space anywhere. (Unless you have it in a
different
.cc file.)
Add this to your source file:
template <typename Type>
Type* Singleton<Type>::ptr;
That worked. Thank you.
Now, why did I have to do that? The static functions that I wrote
inside the class definition were allocated without issue. The code you
had me add just looks like defining a function outside of a class
header except in this case nothing new was added. Is there something I
could have added to the class header that would have avoided that
piece of code you gave me? If I had a non-template class with a static
data member, gcc doesn't complain if I don't redefine it outside of
the header. In other words, why does a template require the code you
gave me and why doesn't a regular class then require something like
the following:
class A
{
public:
static int number;
};
int A::number;
I hope I'm conveying the question clearly. I'm trying to gain a better
understanding to avoid future problems and it will help me remember
all of this if I know why I'm doing it.
Thanks again,
R.
